I noticed if I enable my secondary o2 sensor under the "closed loop" tab my air/fuel ratios and short trim will oscillate +/- 1-2%. The A/F ratio and s.trim are stable in open loop and if I disable the secondary o2. Any ideas as to why?

I wanted to know if the secondary o2 sensor had anything to do with fuel trims. I have tuned my car to +/- 2% short term trims. Its stays there until the secondary o2 voltages goes up (around 0.8-0.9v) then the short term trim goes to +/- 10%. During cruise my o2 voltage is at 0.19v and will spike t...